There have been disclosed wireless sensor network systems (energy harvesting, a battery, etc.) configured to obtain electric power from various energy sources in a plurality of sensor nodes, and to execute unidirectionally or bidirectionally wireless data communications of the sensor information, e.g. switch information, temperature, pressure, with respect to hosts.
Over aging of social infrastructure systems, e.g. bridges, roads, railroad services, and buildings, have emerged as a social problem. Since enormous costs are required for countermeasures against over aging, countermeasures for prolonging a life of these social infrastructure systems are also required.
In conventional wireless sensor network systems, in order to maintain a state where a plurality of sensor nodes can constantly receive signals from a host after transmission of wireless transmission data is completed, it is necessary to constantly turn ON receivers in the plurality of the sensor nodes.
Moreover, in the conventional wireless sensor network systems, if sensor nodes contain not only a transmitting function but a receiving function, the receiving circuit had to be turned ON to keep a reception waiting mode always when its own sensor node do not execute transmission. Accordingly, power consumption is relatively large.